The present invention relates generally to a method of manufacturing a book block with a rounded or a rounded and pressed back. More particularly, the present invention relates to a method of adhering retaining strips to the book block.
For the purpose of manufacturing books having a rounded or pressed back of the book block, it is known for book blocks formed from collated plies to be slip-folded in the adhesive binding machine after the back of the book block has previously been processed and coated with glue over its entire surface. In the process, the slip-folding material is additionally glued to the end papers. The book block prepared in this way is trimmed on three sides and then fed to a book production line.
The coating of the back of the book block with glue over its entire surface, and the slip-folding material applied, impart to the book block a major resisting force against the rounding operation, which force can be overcome only with a great deal of outlay on mechanical engineering. In particular, a preheating section and a performing stations are necessary as well as the actual rounding station to compensate for the resisting force. Also, the rounding operation cannot take place at any speed desired, since the drawing-out of the layer of glue requires a certain amount of time. This results in a restriction on the speed of the machine. In the same way, the resistance of the stiff back of the book block has to be overcome in the pressing operation.
It is an object of the present invention to provide a method of manufacturing a book block with a rounded or a rounded and pressed back, in which the rounding and pressing of the book block can be performed with a substantially reduced outlay on mechanical engineering.
It is another object to provide a method of manufacturing a book block that results in an increase in the cyclical capacity.
It is further an object to provide a rounding and pressing process that is optimum with regard to the quality of the book block.
These and other objects and advantages of the present invention are achieved by a method of manufacturing a book block having outer leaves and a back including longitudinal edges defined by the longitudinal edge of the leaves, comprising the steps of adhering a first plurality of longitudinal retaining strips to the outer leaves and back of the book block and adhering a second plurality of retaining strips across the back of the book block in a direction which is transverse to the direction of the first plurality of retaining strips.
According to another feature of the invention, the method may also comprise the step of adhering at least one third retaining strip across the back of the book block in a direction which is transverse to the direction of the first plurality of retaining strips.
The book block manufactured in accordance with the invention can be rounded and pressed, either when passing through the machine or while at a standstill. The book block may be rounded and pressed with the aid of elements that are of relatively simple mechanical construction, since the forces of resistance are low and it is not necessary to take into account any;time-dependent operations such as drawing-out of materials. In addition to a cost-effective mode of construction, the cyclical speed in the manufacture of rounded book blocks can also be substantially increased.